Perfect for those with sensitive skin, this homemade glycerin soap recipe makes a hard bar of soap that lathers nicely while gently cleansing and moisturizing your skin.
What is glycerin soap?
It sounds like an easy question, but there is really a bit of confusion about what should be called glycerin soap.
When most people think of glycerin soap, they think of translucent soaps. Many think of the translucent melt and pour soaps that can be melted down to make easy, customizable soaps. (Although not all melt and pour soaps are translucent, of course).
What most people don’t know is that there is glycerin in all soap because it is a byproduct of the soap making process.
The difference between translucent “glycerin” soaps and other more opaque soaps with glycerin in them, is that the glycerin soaps have been cooked with certain solvents like sugar, alcohol, and, well, more glycerin, to help make the soap crystals small so that light can pass through. (It’s the soap crystals that reflect light back at our eyes, making soap opaque).
Glycerin soap benefits
Glycerin is a humectant, meaning that it helps retain, or reduce the loss of, moisture.
What’s special about glycerin, though, compared to some other humectants, is that it is an endogenous humectant, meaning we have it naturally in our skin. Glycerin has been shown to help restore moisture and elasticity in the stratum corneum layer of our skin, helping to restore the barrier that protects us.
Interestingly enough, even after you stop using glycerin topically, it can continue to help form a barrier to help prevent moisture loss for up to 2 weeks.
Glycerin soaps are thought to be milder and gentler on the skin. While that probably depends on each particular recipe or soap, I’ve found that this soap has worked well on my son who has sensitive skin with atopic dermatitis. (That said, I still use soaps, or other washing products like gels, sparingly on his skin, and most days only rinse the majority of his skin with water.)
I find this to be a great overall soap for face and body, and I like how it helps reduce acne on my skin.
Watch how I make glycerin soap
The Glycerin Soap Making Process
Making a translucent glycerin soap is really a two part process.
First, you have to make the soap, using a hot process method. (I use my slow cooker which works perfectly for both parts of the process.)
After you have made your soap, you need to dissolve the soap crystals to help allow the light to pass through the soap, making it translucent. To do that, you will use a combination of several different “solvents.”
On my first two attempts, I didn’t spend a lot of time trying to dissolve the crystals. I wasn’t careful to keep the slow cooker well sealed, and I didn’t leave the solvents to work longer, or add more of them, to try to get a more translucent soap.
If getting a more translucent soap is important to you, I’ve given you a range of different solvent values for you to experiment with. I chose to add an amount somewhere in the middle of the given range of each particular solvent. You may want to try adding a smaller amount, and increase, as needed, until your soap gets more translucent. Using a stronger alcohol will also probably help you get a clearer soap.
If you’re really picky about getting translucent soap, I’d suggest reading the book, Making Transparent Soap: The Art Of Crafting, Molding, Scenting & Coloring by Catherine Failor. Her techniques are the ones that most people follow when making both translucent solid soaps and translucent liquid soaps. She has another book about Making Natural Liquid Soaps. If you’re interested in making liquid soaps, I have a couple of liquid soap recipes up on the blog. (You can choose to make a liquid castile soap, or a liquid coconut oil soap, or make both and combine them to get the best of both worlds.)
Choosing oils for a glycerin soap recipe
Because we are going to be using solvents to dissolve some of the soap crystals, it’s best to use oils that make a harder bar of soap. This will help ensure you’ll still end up with a hard, long lasting bar of soap despite the solvent process.
In general, oils that are solid at room temperature tend to make harder bars of soap. (Olive oil can also make a hard bar of soap, but it usually requires a long curing process to get it to harden.) Tallow and coconut oil are great oils for this type of recipe; not only because they make a nice hard bar of soap, but they are also said to be good for making a translucent, rather than cloudy, glycerin soap.
Castor oil is another common oil used in translucent soap making, not because it’s a solid oil that makes a hard bar of soap (because it isn’t, of course), but because castor oil is said to be somewhat of a solvent on its own.
Even after using the solvents, this recipe made very hard bars of soap, and I really love the way it lathers. The coconut oil adds to the cleaning factor of the soap and helps make a bubbly lather. The castor oil helps stabilize that lather. This was the first time I used tallow for making soap because it’s not very easy to find here. (I wanted to make my own, but couldn’t get any butchers to save beef fat for me for rendering tallow.) I have to say that I really love it, and plan on using it more often.
Choosing an alcohol as a solvent
I would have loved to use a consumable alcohol without any added scents or ingredients like Everclear, but I wasn’t able to find anything like that here.
Funny story…
I actually went to the supermarket with my mother-in-law and bought some 70% absinthe because it was the only drinkable alcohol I could find over 50% here in Spain. I was slightly embarrassed buying it, and felt the need to say that it was for making soap. In the end, I felt bad about using an expensive alcohol in my experiments with making a translucent soap, and wasn’t sure how the green coloring would affect the color of my final soap. (I wanted to see what I’d end up with without adding anything at all to it.)
I decided to use some 70% denatured alcohol instead. I was worried about it leaving an unusual scent to my soap, but honestly I don’t notice any off putting fragrances from the alcohol, despite my having forgotten to add any essential oils in the end for fragrance.
I think next time I’d try with a stronger alcohol to see if my soap turns out more translucent. If anybody gives a 96% alcohol, or something similar, a try, I’d love to hear how it goes!
I now have been left with a completely full bottle of absinthe at my house, if anybody wants to come for a party. (Just kidding about the second part.)
Superfatting glycerin soaps
Because excess oils can make for a cloudy soap, I chose not to superfat this soap. (Superfatting is when you add more oils to the soap than what are needed to react with the amount of lye used. Some unreacted oils remain in the soap, and can leave a hydrating film on your skin when you use the soap.)
The excess glycerin in this soap helps compensate and acts as the leftover emollient that helps make a moisturizing soap. I used the same thought process when making my liquid castile soap and liquid coconut oil soap, and find that both are very mild for use on face and body.
Now that I’ve been using this glycerin soap for awhile, I definitely don’t think it’s missing anything, and love it just the way it is. That said, you could always try adding slightly more oil if you prefer to superfat the soap.
Glycerin soap recipe
Homemade Glycerin Soap Recipe (From Scratch)
Makes around 8 bars of soap.
Materials
For the soap
- 304 g distilled water
- 117.7 g lye NaOH
- 440 g tallow
- 200 g castor oil
- 160 g coconut oil
Solvents
- 120 g glycerin Between 98g and 147g
- 300 g 70º alcohol Between 275g and 321g
- 90 g sugar Between 73g and 110g
- 180 g distilled water Between 147g and 244g
Instructions
Make the soap.
- Weigh out the lye in a small, non-metal bowl.
- Weigh out the distilled water in another, larger, non metal bowl.
- In a well ventilated area, carefully pout the lye into the container with the distilled water. You should wear gloves and goggles to protect your eyes and hands. Stir the lye into the water until it is dissolved. The mixture will heat up and get cloudy at first, but will clear up and cool down with time.
- Leave the lye mixture to cool while you weigh out the oils. I find that the easiest way is to place the bowl on a digital scale, tare it, add an oil to the bowl until you reach the right weight. You then tare again before carefully adding the next oil, and between each addition.
- Add the oils to a slow cooker on low heat, and stir them together well. Allow any solid oils like the tallow to melt.
- Carefully add the lye mixture to the melted oils, and gently stir them together. Once the lye solution is fully incorporated into the oils, you can begin to blend them together with an immersion blender.
- Blend with the immersion blender until the mixture thickens to trace. Once the mixture has reached trace, place the lid on the slow cooker and allow the soap mixture to cook for several hours (around 3) until it starts to get transparent.
- You have now made a hot process soap.
Use the solvents to make it translucent.
- Weigh out the alcohol and the glycerin. You will be mixing them together and adding them to your soap. I would have liked to use a high proof alcohol like Everclear, but couldn’t find anything like that here in Spain. I ended up using a 70º denatured alcohol. they say that if you use a higher concentration of alcohol, that it will do a better job of making the soap more transparent. (Perhaps next time I’ll try with a 90+% denatured alcohol. Rubbing alcohol is said to leave an unpleasant scent behind, but I haven’t tried it to verify the difference.)
- Pour the alcohol and glycerin mixture into the soap. You’ll probably end up with chunks of soap floating in the liquid. Try to break them up as best as you can. (I used my immersion blender to break up the chunks and fully incorporate the alcohol and glycerin into the soap. Work in a well-ventilated area for this step and be careful not to have any open flames in the area. (You should always be careful when heating high percentages of alcohol.)
- Cover the crock pot, sealing it as best you can so that the alcohol doesn’t evaporate. (If it evaporates too quickly, it won’t be able to work its magic on the soap.)
If you really have your heart set on making a translucent soap, you should seal your crock pot with some sort of plastic wrap before placing the lid on top. I didn’t have any on hand, and wasn’t really too concerned about making a fully transparent soap, so I just used the regular lid of my crock pot. - Allow the soap to cook, covered and sealed, for around 30 minutes.
- Meanwhile, make your sugar syrup. Weigh out the sugar and water and mix them together in a saucepan over low to medium heat until the sugar has completely dissolved. Remove it from the heat.
- Once the 30 minutes has passed, you can begin to add the sugar solution to the soap. Gently mix it in, trying not to move the soap too much so as not to form a lot of foam or bubbles.
- At this point, you can begin to test the soap for translucence. It will look translucent to the eye, but as it cools, it will become more opaque. The way most people check is by freezing a glass, and adding a small amount of soap to the bottom of the glass to cool it. Keep in mind that you are using a very thin layer of soap, and that when you have a thicker layer it won’t be as translucent.
- To try to get a more translucent soap, you can continue to cook the soap, adding in small amounts of the various solvents and checking the translucence with the frozen glass. (To be honest, I didn’t bother, and just added the sugar, and went right to pouring the soap into the mold. Perhaps next time I’ll try for a more translucent soap, and will give you my tips for what works best.)
- At this point, you can add in any fragrances or colorings. The nice thing about this soap is that because it has been cooking for so long, and has completed the saponification (soap making) phase, you can even use food coloring to color your soaps. You won’t have to worry about the lye reacting with the colorants and changing them as often happens when adding things to cold process soaps.
- Clear the foam off the soap, and carefully pour the soap into your soap molds. Try to be gentle at this stage as any movement can cause foaming of the soap, which will lead to a more opaque soap. (I wasn’t very careful, and my soaps have a more transparent layer on the bottom, with a thin layer that is more opaque at the top, where the bubbly soap settled before hardening.)
- You can skim the foam off and pour it into small soap molds. They will make a more opaque soap that will work just as well as the rest of the soap.
- Allow the soap to set undisturbed overnight.
- The next morning, check the soap for hardness. If it is hard enough, unmold the soap and cut it into bars as needed.
- Allow your soap to cure and dry for several weeks. This is best done by separating the soaps to allow for air flow over them. It’s a good idea to rotate the soaps occasionally so that all sides dry at the same rate. The curing process will allow it to harden and finish any remaining chemical processes to make for a better soap.
My first experience making glycerin soap
The first time I tried to make a glycerin soap, I decided to try using a new wooden soap mold for my newly made soap. I should have experimented with a soap that was easier and quicker to make like my easy, beginner soap.
What happened?
The mold began to leak, and I ended up with my soap solution all over the counter. I scraped up some of it, and tried pouring it into another mold, but by that point I had a lot of parts that were hardening up and floating in the melted soap mixture. I decided that I was going to use my immersion blender to smooth out the mixture before pouring it back into the other mold.
The result?
Because I didn’t let the mixture settle again, I ended up with a more cloudy soap. The soap started to settle on its own leaving a clearer, harder bar of soap on the bottom, and a foamier, opaque soap on top.
What did I learn?
It’s just as important to be careful how you handle the soap when pouring into the molds. You want to be gentle and not incorporate a lot of air into the mixture. That is, unless you are going for this lemon merengue pie look to your soap! (I have to admit that it is kind of cool. The foamy layer is very soft, and almost like a marshmallow.)
Making a loofah soap
I decided to use the translucency of this soap to my advantage, and made loofah soaps. The loofah serves as a gentle, natural exfoliant for bathing.
To make a loofah soap, you can use PVC piping as your soap mold. If you have a PVC pipe cap, you can seal off one end with one of those. If not, you can seal off the end with some heavy plastic and rubber bands.
Add the loofah to the pvc pipe and weigh it down with something. (I used a spoon.)
Once in place, gently pour the soap into the pipe over the loofah.
When the soap has hardened, the easiest way to pull the soap from the mold is to put the pipe into the freezer for at least half an hour. Not only will this help solidify the soap, but it will slightly reduce its size long enough to help you push the soap out of the mold.
Carefully cut the soap into round bars and allow them to cure like you would any other bar of soap.
I’m sure somebody will ask me why the loofah soaps stayed white, while the other soaps turned yellow after during the curing process…
I wish I had an answer. I will say that they were from the same batch, and I didn’t add any colorants or any different ingredients to one versus the other. I poured the bar soaps first, and then filled up the pvc mold for the loofah soaps. If anybody has any ideas about why they aren’t the same color, I’d love to hear them!
Marian
Do you use fractionated coconut oil? That’s what I would like to use. Looking forward to making this soap.
Thanks!
Tracy Ariza, DDS
No, just regular coconut oil. It’s much cheaper. 😉
If you did want to use fractionated coconut oil, you’d have to run the recipe through a lye calculator first. It actually has a different saponification value. (I have a post that explains more about that here.)
mahmoud salem
Hello
I wonder how long does it take for that glycerine soap mold to dry?
Thank you
Tracy Ariza
Hi Mahmoud,
Do you mean how long until you can take it out of the mold? Or how long the total cure time is?
For removing from the mold, you can press into the soap with your finger the next day to see if it’s solid enough to remove without deforming. At that point, you can remove it and cut it into bars.
While you could use it safely immediately, all soaps benefit from a cure time of around a month. During that time, the soap dries further, gets harder, improves lather, etc.
Robert Godfrey
Dear Tracy, I have a serious safety concern about you using (and recomending) the use of denatured alcohol in skincare products. Alcohol is often denatured with methanol, which is toxic through skin contact and deffinately not appropriate for skincare products. Even if the specific brand you use is free of methanol, it will have other unpleasant chemicals added to denature it & most of your readers are unlikely to be sufficiently knowledgeable chemists to differentiate them anyway.
Tracy Ariza
I recommend using consumable alcohol, but not everybody has access to that. It is illegal in many countries to have consumable alcohol at the high enough percentage used for this soap.
My alcohol was specifically intended for cosmetic use, which is why it was not denatured with methanol.
What do you suggest for those who can’t access drinkable ethanol?
Ram D
I think Propylene Glycol (USP grade or Food Grade that is the one used in the Pharma or Food industries) is a good substitute for Denatured (methylated or otherwise) Alcohol.
Let me know your thoughts.
Thanks
Tracy Ariza
Hello,
Yes, I’ve read that you can use propylene glycol. It also is supposed to help make it be a pour-and-melt type of soap.
I’ve never personally used it, though.
Manju
Sprit also can use?
Tracy Ariza
Hi Manju,
It would depend on what type you are referring to.
The higher the alcohol content, the better it will work as a solvent to help dissolve away part of the crystalline structure to make a more translucent soap.
Karlene
Could you use vodka? I use it to make a dry shampoo and to make cleaning supplies.
Tracy Ariza, DDS
You coudl try, but it probably won’t be strong enough to make the soap very translucent. If that doesn’t concern you, though, give it a shot!
Tracie Thibodeau
I have made Glycerin soap using Propylene Glycol USP and it works beautifully. It is also WAY, WAY less expensive than using Everclear or Denatured alcohol.
Ajay Thakur
??
Leigh
Would Everclear alcohol be too strong for this soap recipe? I believe it is legal in my state.
Tracy Ariza
Hi Leigh,
Everclear would be great to use! I wish I could get ahold of it here for all sorts of projects. 😉
Leigh
I just made this soap. I love it! My bars were not real clear though I used plastic wrap to seal it during the cooking process. I only make soap for family & friends so no big deal on clarity. I thought I read something about a recipe adjustment when using Everclear(?)…may have gotten that wrong. I have a 5lb mold too so I may double the recipe. Thank you!!
Tracy Ariza
Hi Leigh,
Yeah, I wasn’t too picky about clarity either (and I probably didn’t worry too much on purpose because I was imagining a lot of people seeing really transparent bars in my pictures and then getting mad if theirs didn’t turn out that well.) 😉
hahahaha
I have been meaning to give it a try, though, to try to get more translucent bars. With Everclear, I’d think you’d need to increase the quantity to get more alcohol into the mixture. If you have a stronger alcohol, you probably don’t need as much.
The problem is that I’ve read that there is a point where you can go too far and instead of getting more translucent, it actually gets cloudier again. I haven’t experimented enough to know if that’s actually true, but I wouldn’t be surprised if it is.
Leigh
I read something here where you mentioned using a smaller amount of alcohol due to the percentage. Am I understanding that correctly? I am about to try this recipe with Everclear next time and though I would ask about it.
Tracy Ariza
Hi Leigh,
I’ve been meaning to give this another try with other alcohols, but still haven’t done it. I think, in theory, you shouldn’t need as much if your alcohol has a higher percentage and may need more if you are using an alcohol with a lower percentage. Again, this all has to do with the appearance of the soap. So, if you don’t have your heart set on getting a more translucent soap, then it’s not going to make a huge difference either way. I, myself, wasn’t too picky with trying to get a highly translucent soap, so I didn’t play too much with the exact amount needed.
Blessing
Please what is the name of the alcohol using I make my soap base but I didn’t put alcohol is not forming is just strong.
Tracy Ariza
I used a pharmaceutical-grade ethyl alcohol. If you can find a strong enough drinkable alcohol, that’s even better. It’s possible to use isopropyl “rubbing” alcohol, but I’ve read that the scent can remain in the final soap.
Cara
Aside from methanol other very toxic compounds can be added to make denatured alcohol. The intent is specifically to make the ethanol toxic! So any kind of denatured alcohol should absolutely not be used for any application where it may have contact with the skin. Some of the additives are known carcinogens. This is incredibly dangerous and just flat out irresponsible to recommend this. I really hope you edit your post so people to not get hurt. Thanks
Tracy Ariza
Again, the denatured alcohol I buy is specifically meant for cosmetics. Most of them sold here are specifically for use on skin. They aren’t made toxic but are given bitter substances to make them unpalatable so people won’t want to drink them.
I do prefer the use of a drinking alcohol if one can find one in a high enough percentage where they live. Unfortunately, in most countries, it is very difficult to obtain that.
Leena
Hello…
Nice soap making receipe. I want to know whether I can add alum (dissolved in water) in melted glycerin? I would like to make a soap of melted glycerin, alum in water, color n perfume. Will this receipe work? Please suggest me something.
Tracy Ariza
Hi Leena,
Well, to be honest, I have no idea what the alum would do in this sort of soap. It’s not something I’ve ever worked with before. May I ask you why you want to use alum? Is it for shaving? (Just curious.)
Leena
Thank you for the reply! Alum works as a deodorising agent. So I want to use that in the soap.
Let’s see. I will try. The only thing I am worried about it is, it should not catch fungus etc if I store it, because of water in the product. And one more thing is alum should not get converted in crystals once soap becomes hard.
Tracy Ariza
Hi Leena,
Soaps are self-preserving. They don’t need a preservative because they have a naturally high pH, which makes them unhabitable for most bacteria and fungi. So, no, you shouldn’t have to worry about the fungus.
I’m not sure about the alum/crystals as I’ve never worked with alum before. I have absolutely no idea about how it would react with soap.
Suyin Di Lauro
Well I got thru the day ! Lol I just finished the recipe with 500g of soup. I had to make this recipe because I am allergic to castor oil, so used olive oil, mango butter, broccoli oil, and the minimum of coconut oil just for cleansing These are the results:
I didn’t have foam, it had a brownish color because of the broccoli oil. To me it came out good! I used 91% regular alcohol. After if there is any strange odor I will let you know.
Tracy Ariza
Hello,
I’m happy it worked out for you.
Normally you have to be careful about switching oils out because soap recipes tend to be quite precise and specific to the oils chosen.
Each oil needs a different amount of lye.
Also, switching oils will completely change the color, texture, lather, cleansing ability, etc.
In the end, though, if it worked and you are happy with it, I’m glad.
Just keep that in mind before making future subs in soap recipes. 😉
Cath
On step #4 in using the solvents section, is that still using low heat as in the making the soap section?
Tracy Ariza
Hi Cath,
Yes, I continue to cook when using the solvents.
Emiliano Massampo
hi
I’d like to know how I can do business with you. To provide the materials
Tracy Ariza
I’m not sure what you mean?
I don’t sell soaps.
You may either tell me what you want here, though, or email me at [email protected]
victoria clement
Thank you for this recipe. I also loved your video, simple and straight forward. Can I substitute the tallow with another oil – making for vegan group and need to use another type of oil.
Tracy Ariza
Hi Victoria,
You can’t just switch out the oils and fats of a soap recipe without running the new recipe through a lye calculator.
That said, I do have a vegan glycerin soap recipe up on the blog.
doha korani
hello dear, i just want to ask u about this glycerin recipe, i see that is free propylen glycol, and what i know that propylene glycol allow the soap to be melted, is ur recipe free propylen glycol could be melted after cure time?
Tracy Ariza
Hello Doha,
I did melt a couple of thin bars as a test and they actually did melt OK. I’m not sure if it melts as nicely as the propylene glycol ones, but definitely much better than trying to melt a normal bar of soap.
Lita
Hi,
I made my first glycerine soap but it is still very very liquid in other day, should I heat it more or is it better to add some fresh made hard soap and mix with soft glycerine soap mixture? pH of my glycerine soap is 8-9m i found it very low…?
Tracy Ariza
Hi Lita,
What recipe did you follow?
The solvents are taking away part of the crystalline structure of the soap, which can soften it. That’s why a good glycerin soap recipe will use lots of hard fats that will make a nice hard bar of soap to begin with. Even after using the solvents on this soap, it is very hard.
I wouldn’t mix it with another soap because that will end up making it very opaque, I think, and it sort of defeats the purpose of all of the hard work you’ve done so far.
Yes, you could try cooking it a bit more. That will help evaporate away some of the liquid and maybe help it harden more quickly.
I’m not sure about the pH. Yes, most soaps are around pH=9. So, if it’s closer to the 9, that isn’t really that unusual. I haven’t tested the pH of this soap. I normally only test it if I see something weird about a particular soap.
May
Hi tracy, i am new in soap. And i still do research. I brought already my ingredients, and since our law are not allowed 70% or more. So i brought 60% which is available here. My question is- should i do the same thing as you written above or should i less the water? I appreciate and hope you read this comment i was a little bit confusing about my 60% alcohol.
Tracy Ariza
Hi May,
The only thing that will be affected is the transparency really. It depends on how important that is to you.
I’d probably try it with the same amount of water, but you may find yourself adding more alcohol if you are trying to achieve a more translucent soap. If you cook it a bit longer afterward, especially if you end up adding more alcohol, the extra water will eventually evaporate out.
Good luck with it!